• Category
  • Length Range
    13.5-38.3 µm
  • Width Range
    3.8-5.5 µm
  • Striae in 10 µm
    11-12 at the valve center, 14-16 at the apices
  • Reported As
    Gomphonema patricki (Kociolek and Stoermer 1995)
    Gomphonema camburnii (Metzeltin and Lange-Bertalot 1998)
    Gomphonema puiggarianum var. aequatorialis (Camburn, Lowe and Stoneburner 1978)



Valves are lanceolate-clavate, widest at the center. The headpole and footpole are narrowly rounded. The axial area is large and lanceolate. The raphe is filiform, with weakly expanded proximal ends that are bent slightly to one side. Striae are uniseriate and very short. The striae are parallel at the valve center and radiate near the apices.

Note that G. camburnii and G. patrickii are heterotypic, or subjective, synonyms of this taxon.


Gomphonema louisiananum was described from material collected at a reservoir in northwestern Louisiana and subsequently reported (as G. patricki) from a lake in the Sierra Nevada Mountains of California (Kociolek et al. 1995). This taxon has also been reported from a stream in South Carolina (Camburn et al. 1978), from low-alkalinity lakes in Minnesota and New York (Camburn and Charles 2000), and from a river in Brazil (Metzeltin and Lange-Bertalot 1998). It was recently found in samples collected from a subalpine lake in the Eagle Cap Wilderness of northeastern Oregon and a lake near sea level on the Haida Gwaii Archipelago of British Columbia (photos below). Although environmental data are not available for these sites, they are primarily sites that have little human influence.

Eaglecap Horseshoelake
Credit: Angela Bohlke, Adventurers and Scientists for Conservation
Horseshoe Lake, Eagle Cap Wilderness, Wallowa County, Oregon: home of Gomphonema patrickiae.
Sample4 506501  Juan Perez Sund  De La Beche Inlet Lake
Credit: Beverly Boynton, Adventurers and Scientists for Conservation
Lake at La Beche Inlet, Juan Perez Sound, Haida Gwaii Archipelago, British Columbia: home of Gomphonema patrickiae.

Original Description

Valve lanceolate, evenly narrowed toward the apex and basis, apex slightly broader. Axial and central area forming a broad lanceolate area. Striae uniformly shortened, slightly radiate throughout most of the valve to almost parallel at the apex. Striae, 12-13 in 10 µm at the centre of the valve to 15 in 10 µm near the apices. Length, 13-30 µm. Breadth, 3-5 µm.

  • Author
    Kalinsky 1984
  • Length Range
    13-30 µm
  • Width
    3-5 µm
  • Striae in 10µm
    12-13 at the valve center, 15 at the apices

Original Images

Gomph Louisiananum Origimag002
Gomphonema louisianum HOLOTYPE
Gomph Louisiananum Origdesc001


Apr 21, 2024 - Extension of Size Range

Prior to this date, length was documented as 17.2-29.1 µm, width as 4.0-5.4 µm. These values were revised to reflect the length and width of a recently found robust population of this taxon. New images from this Eleanor Creek population have replaced those from Oregon and British Columbia. - I. Bishop

Cite This Page

Bahls, L., Bishop, I. (2013). Gomphonema louisiananum. In Diatoms of North America. Retrieved April 21, 2024, from https://diatoms.org/species/gomphonema_louisiananum


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Gomphonema louisiananum from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.